I've been playing guitar for 6 years now, and I'm the shredder/sweep picking/multiple finger tapping/fast legato type of guitar player. I used to practice anywhere from 5-18 hours a day for the majority of my playing years. However lately, as I am older and actually have a social life, I sometimes miss a day or two of practice (usually not more). When I come back to play I end up being really sloppy and it takes me a few hours to warm up and play decently clean.
Does taking days off ruin your playing that fast or am I just psyching myself out? I'm in a band too, and a perfectionist so I always want to be able to shred effortlessly but some days I just can't find the time.
Also, I've noticed that after warming up for a while, my fingering arm starts to hurt on the inside (not muscles wise, but usually right under my wrist, where a watch would go)

1) Establish a daily routine of 1-2 hours so you can just sit down and get something done no matter what. This will build up your technique base so missing a day doesn't set you back nearly as much.

2) Pain in the wrist is troubling. You're probably over-exerting to compensate for sloppiness.

Once you get in the habit of doing a little technique workout every day you'll be able to play in a more relaxed fashion, which ought to take care of the wrist pain. Use your metronome, start slow, etc. Practice at whatever speed allows you to play both accurately and with relaxation.

When I first started playing i'd play up to five hours a day. Now it's like five hours a week. Getting older sucks, but you gotta go to work and other crap. So that keeps me from having an everyday routine like I once had.